The invention relates generally to information systems and more particularly, to systems for monitoring traffic conditions and providing information about those conditions.
On roadways where a significant proportion of the traffic is attributable to commuters, traffic congestion is a routine problem. In some particularly crowded areas, such as metropolitan areas of the country, traffic during commuter hours slows to a stop. While stopped, vehicles are not transporting their drivers, passengers and cargoes to their destinations. The California South Coast Air Quality Management District estimates that Californians alone waste over 400,000 hours a day on the way to work. A by-product of these conditions is that stopped vehicles continue to expel hydrocarbons into the environment.
In addition to the adverse impact on the environment, there is typically an adverse impact on the work force. Many drivers of motor vehicles spend an enormous amount of time getting to and from their workplaces, homes and destinations. These same conditions are experienced during non-commuter times as the result of accidents, maintenance and construction, and unexpected other causes. Additionally, the large amount of time spent on crowded freeways with the inevitable traffic accidents, disabled vehicles, confrontations with other drivers, short tempers, poor drivers, and reckless and dangerous drivers accelerates tension and anger and results in increased stress levels and decreased job performance. By the time many drivers arrive at work, they have had at least one hour of high intensity traffic interaction sometimes including actions taken to avoid damage to property and harm to life and limb.
Many drivers have the option of selecting more than one route to reach their destinations. In many cases, certain routes are congested while others have little traffic. Communicating such traffic information visually on a route-by-route basis to drivers so that they may take the less congested routes would result in a more efficient and balanced use of the roadway system.
Certain locations along the routes offer decision points at which time the driver must decide to take one or another route. At these points, the driver must decide whether to continue ahead on the same route or change routes to get to the destination. After that decision point, the driver is committed unless another decision point lies ahead. In cases where the driver knows before a decision point that slow traffic conditions exist ahead on the present route but an alternate route is less congested, the driver can take the alternate route, thereby relieving traffic congestion, reducing the driver's travel time and reducing hydrocarbon emissions. Receiving timely, accurate, and sufficient information before reaching decision points is essential to the driver's decision process.
In some cases, drivers have flexible work schedules and can decide to arrive at their destinations at a later time if traffic conditions are presently unfavorable. However, sufficient accurate information is needed for the driver to make an informed decision. Delaying their entry onto the roadways will also result in a more balanced use of the roadways. This approach was extremely successful during the 1984 Summer Olympics in Los Angeles.
Several systems for monitoring traffic and informing motorists of traffic conditions have been used. In cities such as New York and Los Angeles for example, certain roadways are monitored by television cameras and sensors embedded in the pavement. These sensors relay information to a central control center where traffic problems are identified. Information can be sent to one or more message boards located on the roadway to inform drivers of problems, and in certain cases, access to particular segments of roadways can be controlled from the central control center by activating traffic control devices.
However in the case of Los Angeles, the message boards are few and give limited information. Although some can recommend an alternate route, a common complaint is that the information on the board is not accurate, current or sufficient to make an informed decision. Additionally, because there are so few message boards, decision points are often missed before the relevant message board is encountered.
In another example of traffic information systems, a series of low power radio transmitters were installed along a roadway in northern San Diego County, California which is heavily traversed by commuter traffic. These transmitters broadcast information on traffic conditions along the roadway on an AM frequency. Complaints from motorists that the information broadcast is not current enough to be helpful and that reception of the radio signal at points along the route is so poor that information could not be received are indicative of the drawbacks of such a system.
An additional consideration with the above systems is that someone other than the driver (the person tasked with making the decision) analyzes the traffic data and draws the conclusions (makes the decision for the driver) which are then communicated to drivers. An alternate system is one where the driver evaluates the information in light of his or her particular situation and draws the conclusion. For example, an operator in a central station may review the images provided by the roadway cameras and determine that a particular roadway is "clogged" and so indicate by the roadway message board along with a recommended alternate route. However, a driver examining the images reflecting conditions on the primary and alternate routes may determine that although the roadway is presently clogged, the pattern of traffic indicates that the roadway will become less congested shortly, or that staying on the primary route will result in the shortest travel time.
Hence, those skilled in the art have recognized the desirability of a traffic condition information system which provides a sufficient amount of current and accurate information concerning traffic conditions prior to decision points and decision times. It has also been recognized that it would be desirable to alert drivers of an upcoming decision point. The present invention fulfills these needs.